U.S. patent number 10,384,893 [Application Number 15/921,832] was granted by the patent office on 2019-08-20 for sheet conveying apparatus, image reading apparatus, and image forming apparatus.
This patent grant is currently assigned to Canon Finetech Nisca Inc.. The grantee listed for this patent is CANON FINETECH NISCA INC.. Invention is credited to Bungo Hasegawa.
![](/patent/grant/10384893/US10384893-20190820-D00000.png)
![](/patent/grant/10384893/US10384893-20190820-D00001.png)
![](/patent/grant/10384893/US10384893-20190820-D00002.png)
![](/patent/grant/10384893/US10384893-20190820-D00003.png)
![](/patent/grant/10384893/US10384893-20190820-D00004.png)
![](/patent/grant/10384893/US10384893-20190820-D00005.png)
![](/patent/grant/10384893/US10384893-20190820-D00006.png)
![](/patent/grant/10384893/US10384893-20190820-D00007.png)
![](/patent/grant/10384893/US10384893-20190820-D00008.png)
![](/patent/grant/10384893/US10384893-20190820-D00009.png)
![](/patent/grant/10384893/US10384893-20190820-D00010.png)
View All Diagrams
United States Patent |
10,384,893 |
Hasegawa |
August 20, 2019 |
Sheet conveying apparatus, image reading apparatus, and image
forming apparatus
Abstract
A sheet conveying apparatus includes a controller to set
conveyance speeds of first, second, and third conveyance rotary
members. The controller sets the conveyance speed of a sheet by the
second conveyance rotary member to a first conveyance speed, which
is the same as a conveyance speed of the sheet by the first
conveyance rotary member, and a second conveyance speed which is
different from the first conveyance speed. When the controller sets
the conveyance speed of the sheet by the first conveyance rotary
member to the first conveyance speed and sets the conveyance speed
of the sheet by the second conveyance rotary member to the second
conveyance speed, the controller sets the conveyance speed of the
sheet by the third conveyance rotary member to a third conveyance
speed which is a speed between the first conveyance speed and the
second conveyance speed.
Inventors: |
Hasegawa; Bungo (Moriya,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
CANON FINETECH NISCA INC. |
Misato-shi, Saitama |
N/A |
JP |
|
|
Assignee: |
Canon Finetech Nisca Inc.
(Misato-shi, JP)
|
Family
ID: |
63581534 |
Appl.
No.: |
15/921,832 |
Filed: |
March 15, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180273319 A1 |
Sep 27, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Mar 22, 2017 [JP] |
|
|
2017-056177 |
Feb 9, 2018 [JP] |
|
|
2018-022280 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65H
5/06 (20130101); B65H 9/002 (20130101); B65H
7/08 (20130101); B65H 2553/82 (20130101); B65H
2801/39 (20130101); B65H 2801/06 (20130101); B65H
2513/104 (20130101); B65H 2513/53 (20130101); B65H
2511/514 (20130101); B65H 2701/1311 (20130101); B65H
2701/1311 (20130101); B65H 2220/01 (20130101); B65H
2513/53 (20130101); B65H 2220/03 (20130101); B65H
2513/104 (20130101); B65H 2220/02 (20130101) |
Current International
Class: |
B65H
5/06 (20060101); B65H 7/08 (20060101); B65H
9/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
H05-201587 |
|
Aug 1993 |
|
JP |
|
H09-24436 |
|
Jan 1997 |
|
JP |
|
2003-312900 |
|
Nov 2003 |
|
JP |
|
2010-042903 |
|
Feb 2010 |
|
JP |
|
Primary Examiner: Bollinger; David H
Attorney, Agent or Firm: Venable LLP
Claims
What is claimed is:
1. A sheet conveying apparatus, comprising: a separation-conveyance
portion configured to separate and convey a sheet; a first
conveyance rotary member, which is provided downstream of the
separation-conveyance portion in a sheet conveyance direction and
is configured to further convey the sheet at a predetermined
conveyance speed in contact with the sheet being conveyed by the
separation-conveyance portion; a second conveyance rotary member,
which is provided downstream of the separation-conveyance portion
in the sheet conveyance direction, is arranged apart from the first
conveyance rotary member by a predetermined interval in a width
direction orthogonal to the sheet conveyance direction, and is
configured to convey the sheet being conveyed by the
separation-conveyance portion in cooperation with the first
conveyance rotary member; a third conveyance rotary member, which
is arranged at a position between a position at a most downstream
end of the separation-conveyance portion and a position at a most
downstream end of the first conveyance rotary member or the second
conveyance rotary member in the sheet conveyance direction and is
configured to convey the sheet being conveyed by the
separation-conveyance portion; and a controller configured to set a
conveyance speed of the first conveyance rotary member, a
conveyance speed of the second conveyance rotary member, and a
conveyance speed of the third conveyance rotary member, wherein the
controller is able to set the conveyance speed of the sheet by the
second conveyance rotary member to a first conveyance speed, which
is the same as a conveyance speed of the sheet by the first
conveyance rotary member, and a second conveyance speed which is
different from the first conveyance speed, and wherein, when the
controller sets the conveyance speed of the sheet by the first
conveyance rotary member to the first conveyance speed and sets the
conveyance speed of the sheet by the second conveyance rotary
member to the second conveyance speed, the controller sets the
conveyance speed of the sheet by the third conveyance rotary member
to a third conveyance speed which is a speed between the first
conveyance speed and the second conveyance speed.
2. A sheet conveying apparatus according to claim 1, wherein, when
the controller sets the conveyance speed of the sheet by the first
conveyance rotary member to the first conveyance speed and sets the
conveyance speed of the sheet by the second conveyance rotary
member to the first conveyance speed, the controller sets the
conveyance speed of the sheet by the third conveyance rotary member
to the first conveyance speed.
3. A sheet conveying apparatus according to claim 1, wherein the
separation-conveyance portion comprises: a separation member
configured to separate sheets; and a conveyance member configured
to convey the sheet in the sheet conveyance direction, and wherein
the third conveyance rotary member is arranged at a position at
which the third conveyance rotary member at least partially
overlaps with the separation member in the width direction as seen
in the sheet conveyance direction and at which the third conveyance
rotary member overlaps with at least one of the first conveyance
rotary member and the second conveyance rotary member in the sheet
conveyance direction as seen in the width direction.
4. A sheet conveying apparatus according to claim 1, further
comprising a sheet detector configured to detect a leading edge of
a sheet to be conveyed at a plurality of positions, wherein, based
on a detection result of the sheet detector, the controller sets
the conveyance speed of the sheet by the second conveyance rotary
member to the first conveyance speed and the second conveyance
speed.
5. A sheet conveying apparatus according to claim 4, wherein the
sheet detector is arranged upstream of the first conveyance rotary
member and the second conveyance rotary member in the sheet
conveyance direction.
6. A sheet conveying apparatus according to claim 4, wherein the
sheet detector is arranged downstream of the first conveyance
rotary member and the second conveyance rotary member in the sheet
conveyance direction.
7. A sheet conveying apparatus according to claim 1, further
comprising: a first drive device configured to drive the first
conveyance rotary member; a second drive device configured to drive
the second conveyance rotary member; and a third drive device
configured to drive the third conveyance rotary member.
8. A sheet conveying apparatus according to claim 1, further
comprising: a first drive source; a second drive source; and a
speed difference setting device configured to set a speed
difference between the first conveyance rotary member and the
second conveyance rotary member by transmitting drive of the first
drive source to the first conveyance rotary member and the second
conveyance rotary member and transmitting drive of the second drive
source in superposition to the drive of the first drive source.
9. A sheet conveying apparatus according to claim 8, further
comprising a drive transmission device configured to transmit the
drive of the first drive source to the third conveyance rotary
member without intermediation of the speed difference setting
device.
10. A sheet conveying apparatus according to claim 1, wherein the
third conveyance speed is an average value of the first conveyance
speed and the second conveyance speed.
11. An image reading apparatus, comprising: an image reading device
configured to read an image of a conveyed sheet; a
separation-conveyance portion configured to separate and convey a
sheet; a first conveyance rotary member, which is provided
downstream of the separation-conveyance portion in a sheet
conveyance direction and is configured to further convey the sheet
at a predetermined conveyance speed in contact with the sheet being
conveyed by the separation-conveyance portion; a second conveyance
rotary member, which is provided downstream of the
separation-conveyance portion in the sheet conveyance direction, is
arranged apart from the first conveyance rotary member by a
predetermined interval in a width direction orthogonal to the sheet
conveyance direction, and is configured to convey the sheet being
conveyed by the separation-conveyance portion in cooperation with
the first conveyance rotary member; a third conveyance rotary
member, which is arranged at a position between a position at a
most downstream end of the separation-conveyance portion and a
position at a most downstream end of the first conveyance rotary
member or the second conveyance rotary member in the sheet
conveyance direction and is configured to convey the sheet being
conveyed by the separation-conveyance portion; and a controller
configured to set a conveyance speed of the first conveyance rotary
member, a conveyance speed of the second conveyance rotary member,
and a conveyance speed of the third conveyance rotary member,
wherein the controller is able to set the conveyance speed of the
sheet by the second conveyance rotary member to a first conveyance
speed, which is the same as a conveyance speed of the sheet by the
first conveyance rotary member, and a second conveyance speed which
is different from the first conveyance speed, and wherein, when the
controller sets the conveyance speed of the sheet by the first
conveyance rotary member to the first conveyance speed and sets the
conveyance speed of the sheet by the second conveyance rotary
member to the second conveyance speed, the controller sets the
conveyance speed of the sheet by the third conveyance rotary member
to a third conveyance speed which is a speed between the first
conveyance speed and the second conveyance speed.
12. An image forming apparatus, comprising: an image forming device
configured to form an image on a conveyed sheet; a
separation-conveyance portion configured to separate and convey a
sheet; a first conveyance rotary member, which is provided
downstream of the separation-conveyance portion in a sheet
conveyance direction and is configured to further convey the sheet
at a predetermined conveyance speed in contact with the sheet being
conveyed by the separation-conveyance portion; a second conveyance
rotary member, which is provided downstream of the
separation-conveyance portion in the sheet conveyance direction, is
arranged apart from the first conveyance rotary member by a
predetermined interval in a width direction orthogonal to the sheet
conveyance direction, and is configured to convey the sheet being
conveyed by the separation-conveyance portion in cooperation with
the first conveyance rotary member; a third conveyance rotary
member, which is arranged at a position between a position at a
most downstream end of the separation-conveyance portion and a
position at a most downstream end of the first conveyance rotary
member or the second conveyance rotary member in the sheet
conveyance direction and is configured to convey the sheet being
conveyed by the separation-conveyance portion; and a controller
configured to set a conveyance speed of the first conveyance rotary
member, a conveyance speed of the second conveyance rotary member,
and a conveyance speed of the third conveyance rotary member,
wherein the controller is able to set the conveyance speed of the
sheet by the second conveyance rotary member to a first conveyance
speed, which is the same as a conveyance speed of the sheet by the
first conveyance rotary member, and a second conveyance speed which
is different from the first conveyance speed, and wherein, when the
controller sets the conveyance speed of the sheet by the first
conveyance rotary member to the first conveyance speed and sets the
conveyance speed of the sheet by the second conveyance rotary
member to the second conveyance speed, the controller sets the
conveyance speed of the sheet by the third conveyance rotary member
to a third conveyance speed which is a speed between the first
conveyance speed and the second conveyance speed.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a sheet conveying apparatus
configured to convey a sheet, and to an image reading apparatus and
an image forming apparatus which include such a sheet conveying
apparatus.
Description of the Related Art
As a sheet conveying apparatus, there has been proposed, as
disclosed in Japanese Patent Application Laid-Open No. H05-201587,
an apparatus which corrects skew feed of a sheet by setting a
conveyance speed difference to a pair of conveyance rollers
arranged apart from each other by a predetermined interval in a
width direction of a sheet orthogonal to a conveyance direction of
a sheet.
However, when the conveyance speed difference is set to the pair of
conveyance rollers as disclosed in Japanese Patent Application
Laid-Open No. H05-201587, there is a fear in that wrinkles are
formed in a sheet between the pair of conveyance rollers and a
roller arranged upstream of the pair of conveyance rollers.
SUMMARY OF THE INVENTION
The present invention provides a sheet conveying apparatus which is
less liable to cause formation of wrinkles in a sheet during sheet
conveyance.
According to one embodiment of the present invention, a sheet
conveying apparatus, comprises:
a separation-conveyance portion configured to separate and convey a
sheet;
a first conveyance rotary member, which is provided downstream of
the separation-conveyance portion in a sheet conveyance direction
and is configured to further convey the sheet at a predetermined
conveyance speed in contact with the sheet being conveyed by the
separation-conveyance portion;
a second conveyance rotary member, which is provided downstream of
the separation-conveyance portion in the sheet conveyance
direction, is arranged apart from the first conveyance rotary
member by a predetermined interval in a width direction orthogonal
to the sheet conveyance direction, and is configured to convey the
sheet being conveyed by the separation-conveyance portion in
cooperation with the first conveyance rotary member; and
a third conveyance rotary member, which is arranged at a position
between a position at a most downstream end of the
separation-conveyance portion and a position at a most downstream
end of the first conveyance rotary member or the second conveyance
rotary member in the sheet conveyance direction and is configured
to convey the sheet being conveyed by the separation-conveyance
portion,
wherein a conveyance speed of the sheet by the second conveyance
rotary member is changeable to a first conveyance speed which is
the same as a conveyance speed of the sheet by the first conveyance
rotary member and a second conveyance speed which is different from
the first conveyance speed, and
wherein, when the conveyance speed of the sheet by the first
conveyance rotary member is set to the first conveyance speed and
the conveyance speed of the sheet by the second conveyance rotary
member is set to the second conveyance speed, a conveyance speed of
the sheet by the third conveyance rotary member is set to a third
conveyance speed which is a speed between the first conveyance
speed and the second conveyance speed.
Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference
to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory view for illustrating a configuration of
an image reading apparatus according to a first embodiment of the
present invention.
FIG. 2 is an enlarged view for illustrating a separation portion
and a skew feed correction portion.
FIG. 3 is an explanatory view for illustrating arrangement of
rollers of the separation portion and the skew feed correction
portion.
FIG. 4A is an explanatory view for illustrating a skew feed
correction portion in a comparative example.
FIG. 4B is a schematic view for illustrating warpage of a sheet in
the comparative example.
FIG. 5 is an explanatory view for illustrating the skew feed
correction portion in the first embodiment.
FIG. 6 is a block diagram for illustrating a control system for an
original conveying apparatus in the first embodiment.
FIG. 7 is a flowchart for illustrating skew feed correction control
for the original conveying apparatus in the first embodiment.
FIG. 8 is an explanatory view for illustrating a skew feed
correction portion in a second embodiment of the present
invention.
FIG. 9 is an explanatory view for illustrating a skew feed
correction portion in a third embodiment of the present
invention.
FIG. 10A is a perspective view for illustrating a planetary gear
mechanism in the third embodiment.
FIG. 10B is a perspective view for illustrating the planetary gear
mechanism, which is partially cut in the illustration.
FIG. 11 is a block diagram for illustrating a control system for an
original conveying apparatus in the third embodiment.
FIG. 12 is a flowchart for illustrating skew feed correction
control for the original conveying apparatus in the third
embodiment.
FIG. 13 is an explanatory view for illustrating a skew feed
correction portion in a fourth embodiment of the present
invention.
FIG. 14 is an explanatory view for illustrating a configuration of
a copying machine in a fifth embodiment of the present
invention.
DESCRIPTION OF THE EMBODIMENTS
Now, with reference to the attached drawings, embodiments of the
present invention will be described in detail.
First Embodiment
A first embodiment of the present invention will be described with
reference to FIG. 1 to FIG. 7. In the first embodiment, a
description will be provided of an embodiment of a sheet conveying
apparatus provided in an image reading apparatus mounted to an
image forming apparatus.
(Image Reading Apparatus)
As illustrated in FIG. 1, an image reading apparatus 100 includes
an image reading unit 110 and an original conveying apparatus 120.
The image reading unit 110 is configured to read an image of an
original D. An original conveying apparatus 120 is capable of
conveying originals D, which are placed on an original placement
unit 30, one after another.
The original conveying apparatus 120 is turnable with respect to
the image reading unit 110 by an opening and closing support
mechanism (not shown) using a hinge (not shown), and is capable of
opening and closing an upper side of the image reading unit 110. On
the upper side of the image reading unit 110, there are arranged an
original glass plate 10 and a flow reading glass plate 20. In the
image reading unit 110, there is arranged a read-scanning unit
50.
The read-scanning unit 50 radiates light to a lower surface of the
original D from a light source (not shown) arranged in a main
scanning direction and allows reflected light to be projected on an
image pickup element (not shown), to thereby read an image. The
read-scanning unit 50 is fixed to a drive belt 54, and a drive
force of a drive motor 53 is transmitted through the drive belt 54
so that the read-scanning unit 50 moves along a guide shaft 56 in
an arrow C direction. For example, a stepping motor or a DC motor
is used as the drive motor 53. A moving direction (arrow C
direction) of the read-scanning unit 50 is referred to as a
sub-scanning direction, and a direction orthogonal to the
sub-scanning direction is referred to as a main scanning
direction.
As modes of reading an original, the image reading apparatus 100 is
capable of performing reading in a fixed-reading mode and a
flow-reading mode, which are to be selected by a user. In the
fixed-reading mode, the image reading unit 110 reads an original D1
placed on the original glass plate 10. A user opens the original
conveying apparatus 120, places the original D1 on the original
glass plate 10, closes the original conveying apparatus 120, and
operates a control panel (135 in FIG. 6) to input a command to
start reading. At this time, the original D1 is pressed by the
original conveying apparatus 120 and fixed on the original glass
plate 10. When the command to start reading is input, the
read-scanning unit 50 reads an image of a lower surface of the
original D1 placed on the original glass plate 10 while moving in
the arrow C direction below the original glass plate 10.
In the flow-reading mode, the image reading unit 110 reads the
original D conveyed by the original conveying apparatus 120 to the
flow reading glass plate 20. A user places the original D on the
original placement unit 30 and operates the control panel (135 in
FIG. 6) to input the command to start reading. The original
conveying apparatus 120 conveys the original D from the original
placement unit one after another to a conveyance passage in the
original conveying apparatus 120, allows the original D to pass
above the flow reading glass plate 20, and delivers the original D
to an original delivery portion 39. At this time, in a state of
being stopped below the flow reading glass plate 20, the
read-scanning unit 50 continuously reads an image of a lower
surface of the original D moving above the flow reading glass plate
20.
(Original Conveying Apparatus)
As illustrated in FIG. 1, the image reading unit 110 being an
example of an image reading device reads an image of the original
(sheet) D having been subjected to skew feed correction performed
by the original conveying apparatus 120 being an example of a sheet
conveying apparatus. The original conveying apparatus 120 conveys
the original D placed on the original placement unit 30 one after
another by a pickup roller 31 and allows the original D to pass
above the flow reading glass plate 20 at a constant speed. The
pickup roller 31 rotates while being held in abutment against an
upper surface of the original D placed on the original placement
unit 30 to bring the original D to a separation portion E being a
separation-conveyance portion.
The separation portion E includes a conveyance roller (conveyance
member) 32, which rotates so as to convey the original in an
original conveyance direction (sheet conveyance direction) G, and a
retard roller (separation member) 33, which forms a separation nip
with the conveyance roller 32, thereby being capable of separating
and conveying a sheet. The retard roller 33 is driven in a
direction of conveying the original in a direction opposite to the
original conveyance direction G of the conveyance roller 32, and is
capable of being driven by the conveyance roller 32. At such
separation portion E, while the conveyance roller 32 conveys an
uppermost original D to a skew feed correction portion F provided
downstream of the separation portion E in the original conveyance
direction G, the retard roller 33 pushes back a multi-fed original,
which is fed together with the original D, to the original
placement unit 30. Further, when one original is conveyed to the
separation portion E, the retard roller 33 is driven by the
conveyance roller 32 to rotate, thereby conveying the original D to
the skew feed correction portion F.
The skew feed correction portion F corrects skew feed of the
original D conveyed from the separation portion E, feeds the
original D to a conveyance path PS1, and gives the original D to a
read roller 36. The read roller 36 is arranged upstream of a platen
roller 35. The read roller 36 conveys the original D having been
subjected to the skew feed correction by the skew feed correction
portion F to the flow reading glass plate 20, and gives the
original D to the read roller 37. A read sensor S2 detects a
reading start timing for the original D. The read-scanning unit 50
reads an image of the original D at the reading timing detected by
the read sensor S2.
The platen roller 35 regulates a rise-up amount of the original D
from the upper surface of the flow reading glass plate 20 to retain
the lower surface of the original D at a focal point position of
the read-scanning unit 50. An image of the original D is read by
the read-scanning unit 50 while the original D is conveyed under a
state in which the rise-up amount of the original D from the upper
surface of the flow reading glass plate 20 is regulated by the
platen roller 35 rotating at a predetermined rotation speed.
The read rollers 36 and 37 rotate at a predetermined rotation speed
to allow the original D to pass above the flow reading glass plate
20 and move at a constant speed. The read roller 37 is arranged
downstream of the platen roller 35, and gives the original D, which
has passed above the upper surface of the flow reading glass plate
20, to a delivery roller 38.
When only an image on one side of the original D is to be read, the
original D whose image has been read is delivered by the delivery
roller 38 to the original delivery portion 39 and stacked thereon.
When images on both sides of the original D are to be read, the
original D whose image on a first side is read is brought by the
delivery roller 38 to a position of protruding toward the original
delivery portion 39, and the delivery roller 38 then stops and
rotate in a reverse direction so that a leading edge and a trailing
edge of the original D is switched to be brought back into the
apparatus. At this time, a flapper 40 is switched to a reverse
conveyance passage PS2. As a result, the original D having been
brought back is fed again to the conveyance path PS1 under a state
in which the front and back sides of the original D are reversed as
compared to the time of reading the first side. The original D is
conveyed above the flow reading glass plate 20 by the read rollers
36 and 37, and an image on a second side of the original D is read
by the read-scanning unit 50. After that, the original D is allowed
to pass through the reverse conveyance path PS2 and the conveyance
path PS1 to set up the page order, and then is delivered by the
delivery roller 38 to the original delivery portion 39 and stacked
thereon.
(Skew Feed Correction Portion)
As illustrated in FIG. 1, in the original conveying apparatus 120,
the skew feed correction portion F is provided downstream of the
separation portion E in order to correct skew feed of the original
D before the original D having been separated by the separation
portion E arrives at the read roller 36. In the drawings to be
referred in the following description, members which are not
required to be illustrated are omitted for ease of understanding of
a positional relationship of members. FIG. 2 is an enlarged view
for illustrating the separation portion E and the skew feed
correction portion F. FIG. 3 is an explanatory view for
illustrating arrangement of rollers of the separation portion E and
the skew feed correction portion F.
As illustrated in FIG. 2, the separation portion E is arranged
downstream of the pickup roller 31 apart by a predetermined
distance in the original conveyance direction G. The skew feed
correction portion F is arranged downstream of the separation
portion E apart by a predetermined distance in the original
conveyance direction G. Skew feed detection sensors S1a and S1b are
arranged between the separation portion E and the skew feed
correction portion F. The pickup roller 31 rotates while being held
in abutment against the original D to feed the original D to the
separation portion E.
As illustrated in FIG. 3, the separation portion E is arranged
downstream of the skew feed correction portion F in the original
conveyance direction G, and is capable of separating and conveying
the original D one after another from a plurality of stacked
originals. The skew feed correction portion F includes a correction
roller 34a being a first conveyance rotary member, a correction
roller 34c being a second conveyance rotary member, and a
correction roller 34b being a third conveyance rotary member, which
are capable of conveying the original (sheet) D. The correction
roller 34c is arranged apart by a predetermined interval from the
correction roller 34a in a width direction H orthogonal to the
original conveyance direction (sheet conveyance direction) G of the
correction roller 34a. The correction roller 34b, as described
later in detail, is arranged between the correction roller 34a and
the correction roller 34c in the width direction H orthogonal to
the original conveyance direction G. The correction rollers 34a,
34b, and 34c are held in abutment against rollers 34d, 34e, and
34f, respectively, to form nips Na, Nb, and Nc capable of nipping
the original D. The skew feed detection sensors S1a and S1b being
sheet detectors are arranged apart from each other by a
predetermined interval on the same line parallel to the width
direction H orthogonal to the original conveyance direction G, and
are capable of detecting an original to be conveyed. Through
measurement of a difference in timings at which the skew feed
detection sensors S1a and S1b detect a leading edge of an original
D' indicated by broken lines, a skew feed amount of the original D'
is determined.
The correction roller 34c is capable of conveying the original D in
cooperation with the correction roller 34a, and a peripheral speed
(hereinafter referred to as "conveyance speed") of the correction
roller 34c can be changed to a conveyance speed which is different
from a conveyance speed of the correction roller 34a. With this
configuration, in the skew feed correction portion F, different
conveyance speeds are set to the correction rollers 34a and 34c
based on the skew feed amount of the original D' determined in
accordance with detection results of the skew feed detection
sensors S1a and S1b. With this configuration, the original D' is
rotated within a conveyance plane so that, as illustrated with the
original D indicated by solid lines, the skew feed of the original
D' is corrected. After the skew feed of the original D' is
corrected, in the skew feed correction portion F, the same
conveyance speed is set to the correction rollers 34a and 34c, and
the original having been subjected to skew feed correction is
conveyed as it is.
(Comparative Example)
FIG. 4A and FIG. 4B are explanatory views for illustrating a skew
feed correction portion F' in a comparative example. As illustrated
in FIG. 4A, also for the skew feed correction portion F' in the
comparative example, a conveyance speed difference is set to the
pair of correction rollers 34a and 34c, which are arranged apart
from each other by a predetermined distance in the width direction
of the original D, to rotate the original D within the conveyance
plane, to thereby correct the skew feed of the original D. However,
the case of the comparative example is different from the
above-mentioned embodiment in that a correction roller is not
arranged between the correction rollers 34a and 34c.
Therefore, in the case of the configuration including the skew feed
correction portion F' in the comparative example, there is a fear
in that wrinkles are formed in the original D to be conveyed. For
example, the separation portion E is arranged upstream of the
correction rollers 34a and 34c in the original conveyance direction
G, and conveyance resistance such as friction resistance or
pull-out resistance by the separation portion E acts on a center
portion of the original D in the width direction H. Thus, both
sides of the original D are conveyed by the correction rollers 34a
and 34c under a state in which the center portion of the original D
is pulled by the separation portion E, with the result that warpage
as illustrated in FIG. 4A is liable to occur in the original D.
When the warpage occurs in the original D, there is a fear in that
wrinkles are formed due to skew feed of the original D or due to
nipping of the warpage by the rollers.
A more specific description will be provided. For example, when a
plurality of originals are conveyed in a superposed state
(multi-fed), in the separation portion E, while the conveyance
roller 32 rotates in a forward direction to feed the uppermost
original D to the skew feed correction portion F, the retard roller
33 rotates in a reverse direction to push back the multi-fed
original to an upstream side. Then, at the moment at which the
multi-fed original is pushed out toward the upstream side, the
retard roller 33 having been rotating in the reverse direction
applies a significant amount of friction to the lower surface of
the uppermost original D to pull the original D toward the upstream
side. As a result, the original D is pulled between the correction
rollers 34a and 34c arranged apart in the width direction and the
separation portion E arranged on the upstream side, and the
original D is twisted thereby. Accordingly, as illustrated in FIG.
4B, the warpage W occurs in the original D between the correction
roller 34a and 34c and the separation portion E. That is, when the
skew feed correction portion F' is arranged downstream of the
separation portion E, the warpage W occurs in the original D due to
the conveyance resistance which is generated when the skew feed
correction portion F' pulls out the original D passing through the
separation portion E. Wrinkles corresponding to the warpage W may
be formed in the original D which is conveyed to the skew feed
correction portion F' in the above-mentioned state. Further, the
phenomenon described above may occur also in a case in which, for
example, a separation pad having a large friction force with
respect to a sheet is used in place of the retard roller 33.
Thus, with the configuration disclosed in Japanese Patent
Application Laid-Open No. H05-201587 mentioned above, between the
separation portion and the rollers configured to correct the skew
feed, a conveyance roller configured to convey a sheet is provided
at a position substantially the same as the rollers configured to
correct the skew feed in the width direction orthogonal to the
original conveyance direction. Therefore, the conveyance passage
for conveying the sheet is extended, and downsizing of the
apparatus is hindered.
(Skew Feed Correction Portion in First Embodiment)
Therefore, in the first embodiment, as illustrated in FIG. 3, the
correction roller 34b is arranged at a position which is located
between the correction rollers 34a and 34c in the original
conveyance direction G as seen in the width direction H orthogonal
to the original conveyance direction G and overlaps with a position
of the retard roller 33 in the width direction H as seen in the
original conveyance direction G. With this configuration, the
warpage W of the original D due to the conveyance resistance of the
separation portion E is alleviated, thereby suppressing formation
of wrinkles. It is preferred that the position of the correction
roller 34b be located, as seen in the width direction H, between a
position of the retard roller 33 at the most downstream end in the
original conveyance direction G and a position of a most downstream
end of the correction rollers 34a and 34c in the original
conveyance direction G. Further, in addition, it is preferred that
the position of the correction roller 34b be located at a position
at which, as seen in the original conveyance direction G, at least
a part of the correction roller 34b overlaps with the position of
the retard roller 33 in the width direction H. With reference to
FIG. 5, a configuration of the skew feed correction portion F in
the first embodiment will be described in detail.
As illustrated in FIG. 5, for skew feed correction, the correction
roller 34a being an example of the first conveyance rotary member
and the correction roller 34c being an example of the second
conveyance rotary member are capable of conveying the original D
with a conveyance speed difference at positions apart from each
other in the width direction H orthogonal to the original
conveyance direction G. In the first embodiment, the correction
roller 34b is arranged between the correction roller 34a and the
correction roller 34c. The separation portion E is arranged
upstream of the correction roller 34b in the original conveyance
direction G. In the first embodiment, the correction roller 34b is
arranged at a position of overlapping with the retard roller 33 of
the separation portion E as seen in the original conveyance
direction G. That is, the correction roller 34b is arranged at a
center position between the correction roller 34a and the
correction roller 34c in the width direction H. The separation
portion E is arranged upstream of the correction rollers 34a and
34c in the original conveyance direction G at a position
corresponding to a center position between the correction roller
34a and the correction roller 34c in the width direction H. In
other words, the correction roller 34b is arranged at the same
position as the separation portion E in the width direction H
orthogonal to the original conveyance direction G of the original
D.
Thus, the correction roller 34b conveys the original (sheet) D at
an intermediate position between the correction roller 34a and the
correction roller 34c so as to overcome the conveyance resistance
generated in the separation portion E. With this action, the
correction roller 34b pulls the original D toward the downstream
side while overcoming the conveyance resistance generated in the
separation portion E, thereby alleviating the warpage W which
occurs between the correction rollers 34a and 34c and the
separation portion E.
The correction rollers 34a, 34b, and 34c are arranged so that, as
illustrated in FIG. 5, respective rotary shafts 34a1, 34b1, and
34c1 of the correction rollers 34a, 34b, and 34c are arranged on
the same straight line in the width direction H orthogonal to the
original conveyance direction G. In the first embodiment, the
correction rollers 34a, 34b, and 34c are driven by stepping motors
M1, M3, and M2, respectively, which are driven independently. That
is, the skew feed correction portion F in the first embodiment
includes the stepping motor M1 being a first drive device, the
stepping motor M2 being a second drive device, and the stepping
motor M3 being a third drive device. The stepping motor M1 is
configured to drive the correction roller 34a to rotate. The
stepping motor M2 is configured to drive the correction roller 34c
to rotate. The stepping motor M3 is configured to drive the
correction roller 34b to rotate.
Further, in the first embodiment, the skew feed detection sensors
S1a and S1b which are capable of detecting a leading edge of the
original D to be conveyed are arranged upstream of the correction
rollers 34a, 34b, and 34c in the original conveyance direction G.
The skew feed detection sensors S1a and S1b are arranged apart from
each other by a predetermined interval in the width direction H so
that respective detection positions for detecting the original D
are positioned on the same straight line parallel to the width
direction H orthogonal to the original conveyance direction G.
Therefore, the leading edge of the original D fed by the separation
portion E is detected by the skew feed detection sensors S1a and
S1b at timings depending on the skew feed amount of the original D.
The skew feed detection sensors S1a and S1b are each a reflected
light sensor configured to detect reflected light of infrared light
emitted from a light source (LED) with a photodiode.
Now, it is assumed that, in order to correct the skew feed of the
original D to be conveyed, the correction roller 34a is set to a
first conveyance speed, and the correction roller 34c is set to a
second conveyance speed different from the first conveyance speed.
In this case, the conveyance speed of the correction roller 34b is
set to a third conveyance speed between the first conveyance speed
and the second conveyance speed. That is, through control by a
controller 150, the stepping motor M3 drives the correction roller
34b so that the correction roller 34b conveys the original D at an
intermediate conveyance speed between the conveyance speed of the
correction roller 34a and the conveyance speed of the correction
roller 34c. For example, a rotation speed of the stepping motor M3
is controlled so that the correction roller 34b conveys the
original D at a conveyance speed which is an average between the
conveyance speed of the correction roller 34a and the conveyance
speed of the correction roller 34c.
The stepping motor M3 drives the correction roller 34b without
involvement to drive of the correction rollers 34a and 34c.
Therefore, any complicated mechanism such as planetary gears is not
required, and hence reduction in number of components of the
mechanism and downsizing are achieved. In the first embodiment, the
correction roller 34b is driven by the stepping motor M3 through
intermediation of toothed pulleys 25 and 26 and a toothed belt
27.
As illustrated in FIG. 6, the controller 150 includes a ROM 151, a
RAM 152, and a CPU 153. The ROM 151 stores, for example, a program
corresponding to a control procedure. The CPU 153 is configured to
execute control for components while reading the program. The RAM
152 stores work data and input data. The CPU 153 is configured to
execute control by referring to data stored in the RAM 152 based
on, for example, the above-mentioned program. The control panel 135
is operated by a user to perform various input and setting with
respect to the image reading apparatus 100.
A feed motor M4 drives the pickup roller 31 and the separation
portion E. The controller 150 engages the feed clutch 59 to
transmit drive of the feed motor M4 to the pickup roller 31, and
disengages the feed clutch 59 to cut transmission of the drive of
the feed motor M4. The controller 150 controls the stepping motors
M1, M2, and M3 to drive the correction rollers 34a, 34b, and 34c.
The controller 150 sets conveyance speeds of the correction rollers
34a and 34c based on detection results of the skew feed detection
sensors S1a and S1b.
Specifically, the controller 150 calculates a skew feed amount of
the original D based on a difference in timings at which the skew
feed detection sensors S1a and S1b detect the leading edge of the
original D. Based on the calculated skew feed amount, the
controller 150 controls the stepping motors M1 and M2 to drive the
correction rollers 34a and 34c to rotate, and sets a conveyance
speed difference corresponding to the skew feed amount between the
correction roller 34a and the correction roller 34c. Then, the
controller 150, while maintaining the conveyance speed difference,
drives the correction rollers 34a and 34c for a time period
corresponding to the skew feed amount. With this action, the
original D is rotated within the conveyance plane, thereby
correcting the skew feed of the original D.
In accordance with detection of the trailing edge of the original D
by the skew feed detection sensors S1a and S1b, the controller 150
determines a feed timing of a next original by the pickup roller
31. Further, the controller 150 performs size determination for the
original D in accordance with detection timings for the leading
edge and the trailing edge of the original D by the skew feed
detection sensors S1a and S1b.
Next, a specific example of control of the skew feed correction
will be described with reference to FIG. 5. As illustrated in FIG.
5, when the original D is conveyed with skew feed, during a time
period of from detection of the leading edge of the original D by
the skew feed detection sensor S1a to detection of the leading edge
of the original D by the skew feed detection sensor S1b, the
original D is conveyed by a distance d [mm]. When the conveyance
speed of the original D is X [mm/sec], the time period .DELTA.T
[sec] of from detection of the leading edge of the original D by
the skew feed detection sensor S1a to detection of the leading edge
of the original D by the skew feed detection sensor S1b satisfies a
relationship given by the following expression. .DELTA.T=d/X
The controller 150 calculates the distance d based on a measurement
value of the time period .DELTA.T and the known conveyance speed X,
and determines the skew feed amount of the original D based on the
distance d and the arrangement interval of the skew feed detection
sensors S1a and S1b. Then, based on the skew feed amount, the
controller 150 determines a conveyance speed difference between the
correction rollers 34a and 34c for correction of the skew feed.
Then, for example, the controller 150 increases the conveyance
speed of the correction roller 34c to be higher than an initial
conveyance speed given before the skew feed correction. In this
case, the conveyance speed of the correction roller 34a may be
maintained at the initial conveyance speed without any change, or
the conveyance speed of the correction roller 34a may be reduced to
be lower than the initial conveyance speed. Further, both the
changes in conveyance speeds of the correction roller 34a and the
correction roller 34c may be performed simultaneously.
In any case, the conveyance speed of the correction roller 34b at
the center is set to a conveyance speed between the conveyance
speed of the correction roller 34a and the conveyance speed of the
correction roller 34c. In particular, the conveyance speed of the
correction roller 34b is set to a median value. When one roller of
the correction rollers 34a and 34c is increased in speed, and
another roller is reduced in speed at a rate which is the same as
that of the rate of increase in speed of the one roller, the
conveyance speed of the correction roller 34b remains at the
initial conveyance speed.
The initial conveyance speeds of the correction rollers 34a, 34b,
and 34c are equal. Further, when the original D involves skew feed
in a direction opposite to that illustrated in FIG. 5, only the
order of detection of the leading edges of the original at the skew
feed detection sensors S1a and S1b is changed, and the same control
is executed.
With reference to FIG. 6 and FIG. 7, a description will be provided
of an example of a flow of control in the first embodiment
described above. When a command to start image reading is given,
the CPU 153 engages the feed clutch 59 and, at the same time,
operates the stepping motors M1, M2, and M3 (Step S11).
At this time, the pickup roller 31, the conveyance roller 32, and
the retard roller 33 operate, and the correction rollers 34a, 34b,
and 34c rotate at the same speed to wait for the original D. After
elapse of a predetermined time period, when none of the skew feed
detection sensors S1a and S1b detects the leading edge of the
original D (NO in Step S12), the CPU 153 stops all the motors (Step
S17), determines that conveyance abnormality due to jamming of the
original D has occurred, and informs a user of the jamming of the
original (sheet) (Step S19).
When at least one of the skew feed detection sensors S1a and S1b
detects the leading edge of the original D before elapse of a
predetermined time period (YES in Step S12), the CPU 153 determines
whether or not there is a time difference between detections by the
skew feed detection sensors S1a and S1b (Step S13). When there is
the time difference (YES in Step S13), the CPU 153 calculates a
skew feed amount of the original D based on the detection results,
and changes rotation speeds of the stepping motors M1 and M2 in
accordance with the skew feed amount (Step S18). At this time, the
changes in rotation speed of the stepping motors M1 and M2 are
maintained for a time period corresponding to the skew feed amount
(time difference in Step S13). After elapse of this time period,
the rotation speeds of the stepping motors M1 and M2 are set back
to speeds which cause the correction rollers 34a and 34c to rotate
at the same speed (Step S14).
When there is no time difference between the detections by the skew
feed detection sensors S1a and S1b in Step S13, that is, when the
skew feed detection sensors S1a and S1b detect the leading edge of
the original D at the same time (NO in Step S13), the CPU 153
determines that no skew feed occurs, and continues the rotation of
the stepping motors M1 and M2 at the same speed (Step S14).
When the skew feed detection sensors S1a and S1b are not turned off
after elapse of the predetermined time period (NO in Step S15), the
CPU 153 determines that conveyance abnormality due to jamming of
the original D has occurred, and informs a user of the sheet jam
(Step S19). At this time, the CPU 153 disengages the feed clutch 59
and turns off supply of power to the stepping motor M1, M2, and M3
to stop conveyance of the original D.
Meanwhile, when the skew feed detection sensors S1a and S1b are
turned off before elapse of the predetermined time period (YES in
Step S15), the CPU 153 gives the original D to the read rollers 36
and 37. Then, image reading is performed, and thereafter the
original D is delivered to the original delivery portion 39 by the
delivery roller 38. When there is a next original (YES in Step
S16), the CPU 153 continues feeding of the original (Step S11).
When there is no next original (NO in Step S16), the feeding is
ended.
In the first embodiment, the separation portion E stops conveyance
at the timing at which the skew feed detection sensors S1a and S1b
detect the original D, and restarts conveyance at the time of
starting conveyance of the next original D. During correction of
the skew feed by the skew feed correction portion F, the separation
portion E is driven to rotate by the original D. Therefore, the
separation portion E does not hinder the skew feed correction
operation for the original D by the skew feed correction portion F.
As long as there is adopted the configuration of not hindering the
skew feed correction operation for the original D by the skew feed
correction portion F as described above, there may also be adopted
a configuration of separating the separation portion E apart to
release nipping of the sheet.
In the first embodiment, the correction roller 34b is provided at
the intermediate position between the correction rollers 34a and
34c to convey the sheet by the correction roller 34b. Therefore,
while the skew feed of the original D is corrected by setting the
conveyance speed difference to the correction rollers 34a and 34c,
formation of the wrinkles in the original D due to the conveyance
resistance or pull-out resistance of the separation portion E can
be reduced. In particular, in the first embodiment, the correction
roller 34b and the separation portion E are provided at the same
position in the width direction orthogonal to the original
conveyance direction G. Therefore, a conveyance force resisting
against the resistance of the separation portion E can be generated
efficiently by the correction roller 34b, and hence the wrinkles
are less liable to be formed in the original. Further, the
correction roller 34b is positioned at the center between the
correction roller 34a and the correction roller 34c. Therefore,
conveyance by the correction roller 34b can be performed with less
influence on the change in conveyance speed of the correction
rollers 34a and 34c for the skew feed correction.
As described above, in the first embodiment, even with the
configuration in which the correction rollers 34a and 34c are
closely arranged downstream of the separation portion E, pulling of
the original by the separation portion E and the skew feed
correction portion F can be reduced by the correction roller 34b
arranged between the correction rollers 34a and 34c, and hence
formation of the wrinkles in the original D is less likely to
occur. Therefore, the correction rollers 34a and 34c can be
arranged close downstream of the separation portion E, thereby
being capable of achieving downsizing of the original conveying
apparatus 120.
Further, in the first embodiment, stepping motors, which are
excellent in speed responsiveness, are employed as drive sources
for the correction rollers 34a, 34b, and 34c. Therefore, detection
information of the skew feed detection sensors S1a and S1b can be
promptly reflected to a pulse rate change in motor drive pulse.
However, the drive sources for the correction rollers 34a, 34b, and
34c are not limited to the stepping motors, and may be other motors
such as DC motors.
Second Embodiment
A second embodiment of the present invention will be described with
reference to FIG. 8. In the above-mentioned first embodiment, the
skew feed detection sensors S1a and S1b are arranged upstream of
the correction rollers 34a, 34b, and 34c. In the second embodiment,
the skew feed detection sensors S1a and S1b are arranged downstream
of the correction rollers 34a, 34b, and 34c. Other configurations
and actions are the same as those of the above-mentioned first
embodiment. Therefore, redundant illustration and description are
omitted or simplified, and portions different from the first
embodiment will be mainly described.
In the second embodiment, the skew feed detection sensors S1a and
S1b are arranged downstream of the correction rollers 34a, 34b, and
34c in the original conveyance direction G. The skew feed detection
sensors S1a and S1b are arranged apart from each other by a
predetermined interval in the width direction H so that respective
detection positions for detecting the leading edge of the original
are positioned on the same straight line parallel to the width
direction H orthogonal to the original conveyance direction G.
In the second embodiment, under a state in which the original D is
nipped by the correction rollers 34a, 34b, and 34c and being
conveyed, the skew feed amount of the original D is detected by the
skew feed detection sensors S1a and S1b. Therefore, the skew feed
amount of the original D can be detected under a state in which the
conveyance state is more stable than that in the first embodiment
in which the skew feed amount of the original D being conveyed by
the separation portion E is detected, thereby being capable of
performing more accurate skew feed correction.
In the second embodiment, the skew feed detection sensors S1a and
S1b detect the skew feed amount of the sheet being conveyed by at
least the correction roller 34b. Therefore, the skew feed amount
can be detected under a state in which an edge having been
alleviated in warpage through conveyance by the correction roller
34b is linear, thereby being capable of controlling the skew feed
correction by the correction roller 34a and the correction roller
34c based on output from the stable skew feed detection sensors S1a
and S1b.
In the second embodiment, a conveyance distance from passage of the
leading edge of the original D through the skew feed detection
sensors S1a and S1b to passage of the trailing edge of the original
D through the correction rollers 34a, 34b, and 34c is short.
Therefore, when the skew feed amount of the original D having a
small length in the original conveyance direction G is to be
corrected, there is a fear in that the skew feed correction is not
completed before the trailing edge of the original D passes through
the correction rollers 34a, 34b, and 34c. Therefore, in the case of
the original D having a small length in the original conveyance
direction G, it is preferred that nip time required for the skew
feed correction be secured by reducing the conveyance speed.
Third Embodiment
A third embodiment of the present invention will be described with
reference to FIG. 9 to FIG. 12. In the above-mentioned first and
second embodiments, the correction rollers 34a, 34b, and 34c are
driven by the independent stepping motors M1, M2, and M3,
respectively. In the third embodiment, the correction rollers 34a,
34b, and 34c are driven by a common stepping motor M11, and the
conveyance speed difference is set to the correction rollers 34a
and 34c by an operation mechanism driven by a stepping motor M12.
Other configurations and actions are the same as those of the
above-mentioned first embodiment. Therefore, redundant illustration
and description are omitted or simplified, and portions different
from the first embodiment will be mainly described.
In the third embodiment, the skew feed detection sensors S1a and
S1b are arranged upstream of the correction rollers 34a, 34b, and
34c in the original conveyance direction G. The skew feed detection
sensors S1a and S1b are arranged apart from each other by a
predetermined interval in the width direction H so that respective
detection positions for detecting the leading edge of the original
D are positioned on the same straight line parallel to the width
direction H orthogonal to the original conveyance direction G.
As illustrated in FIG. 9, a skew feed correction portion F1 in the
third embodiment includes the stepping motor M11 being a first
drive source, the stepping motor M12 being a second drive source, a
speed-changing portion being a speed difference setting device (a
speed difference forming device), and a third drive transmission
portion 80 being a drive transmission device. The speed-changing
portion 70 includes a first drive transmission portion 71, a second
drive transmission portion 72, and planetary gear mechanisms 60a
and 60c. The speed-changing portion 70 is capable of transmitting
drive of the stepping motor M11 to the correction roller 34a being
the first conveyance rotary member and the correction roller 34c
being the second conveyance rotary member. Further, the
speed-changing portion 70 is capable of setting the speed
difference between the correction roller 34a and the correction
roller 34c by transmitting drive of the stepping motor M12 in
superposition with the drive of the stepping motor M11.
The first drive transmission portion 71 transmits drive from the
stepping motor M11 to the planetary gear mechanisms 60a and 60c.
Specifically, the drive transmission portion 71 includes a pulley
25e fixed to a rotary shaft of the stepping motor M11, pulleys 25c
and 25a fixed to shafts of the planetary gear mechanisms 60a and
60c on drive input side, respectively, and a belt 27e stretched
around the pulleys 25e, 25c, and 25a.
The second drive transmission portion 72 also transmits drive from
the stepping motor M12 to the planetary gear mechanisms 60a and
60c. Specifically, the second drive transmission portion 72
includes a gear 26 fixed to a rotary shaft of the stepping motor
M12, and the gear 26 is in mesh with an outer gear portion 64,
which will be described later and is formed on an outer peripheral
surface of a ring gear 66a of the planetary gear mechanism 60a
described later. The outer gear portion 64a of the ring gear 66a is
in mesh with an outer gear portion 64c, which is adjacent to the
outer gear 64a and is formed on an outer peripheral surface of a
ring gear 66c of the planetary gear mechanism 60c.
(Planetary Gear Mechanism)
A description will be provided of the above-mentioned planetary
gear mechanisms 60a and 60c with reference to FIG. 9, FIG. 10A, and
FIG. 10B. The planetary gear mechanisms 60a and 60c have the same
configuration. Therefore, in FIG. 10A and FIG. 10B, the suffixes a
and c which distinguish the two planetary gear mechanisms 60a and
60c are omitted. As illustrated in FIG. 10A, the planetary gear
mechanism 60 includes a sun gear 61, a ring gear 66, planetary
gears 62, and a carrier 63.
The sun gear 61 is fixed to each of the rotary shafts 610a and
610c. As illustrated in FIG. 9, the rotary shaft 610a fixed to the
sun gear 61a of the planetary gear mechanism 60a is fixed to a
pulley 25h, and is connected to the correction roller 34a through
intermediation of a belt 27h and a pulley 25i so as to be capable
of transmitting drive. The rotary shaft 610c fixed to the sun gear
61c of the planetary gear mechanism 60c is fixed to a pulley 25j,
and is connected to the correction roller 34c through
intermediation of a belt 27j and a pulley 25k so as to be capable
of transmitting drive.
The ring gear 66 is a cylindrical gear which is arranged so as to
be coaxial with the sun gear 61 and surround a periphery of the sun
gear 61, and has an inner gear portion 65 on an inner peripheral
surface and the outer gear portion 64 on an outer peripheral
surface. As described above, the outer gear portion 64a of the
planetary gear mechanism 60a and the outer gear portion 64c of the
planetary gear mechanism 60c are in mesh with each other.
In a space formed between the sun gear 61 and the ring gear 66, a
plurality of (two in the illustrated example) planetary gears 62
are arranged so as to be in mesh with the sun gear 61 and the inner
gear portion 65. Respective rotary shafts of the plurality of
planetary gears 62 are supported by the carrier 63. Therefore, the
planetary gears 62 are rotatable about respective axes, and are
revolvable together with the carrier 63 around the sun gear 61. A
rotation center shaft 630 of the carrier 63 is coaxial with a
rotation center shaft of the sun gear 61, and is connected to the
first drive transmission portion 71. That is, a rotation center
shaft 630a of the planetary gear mechanism 60a is fixed to the
pulley 25a of the first drive transmission portion 71. A rotation
center shaft 630c of the planetary gear mechanism 60c is fixed to
the pulley 25c of the first drive transmission portion 71.
The third drive transmission portion 80 is capable of transmitting
the drive of the stepping motor M11 to the correction roller 34b
being the third conveyance rotary member without intermediation of
the speed-changing portion 70. Specifically, the third drive
transmission portion 80 includes a pulley 25b around which the belt
27e is stretched, a pulley 25f connected to the pulley 25b through
intermediation of the rotary shaft 81, a pulley 25g fixed to the
rotary shaft of the correction roller 34b, and a belt 27f stretched
around the pulleys 25f and 25g. Thus, the drive of the stepping
motor M11 is transmitted to the correction roller 34b through
intermediation of the pulley 25e, the belt 27e, the pulley 25b, the
rotary shaft 81, the pulley 25f, the belt 27f, and the pulley
25g.
The drive of the stepping motor M11 is transmitted also to carriers
63a and 63c of the planetary gear mechanisms 60a and 60c through
intermediation of the pulley 25e, the belt 27e, and the pulleys 25a
and 25c. The planetary gears 62a and 62c revolve together with the
carriers 63a and 63c so that the sun gears 61a and 61c rotate. The
rotation of the sun gear 61a is transmitted to the correction
roller 34a through intermediation of the rotary shaft 610a, the
pulley 25h, the belt 27h, and the pulley 25i. The rotation of the
sun gear 61c is transmitted to the correction roller 34c through
intermediation of the rotary shaft 610c, the pulley 25j, the belt
27j, and the pulley 25k.
As described above, the drive of the stepping motor M12 is
transmitted to the outer gear portion 64a of the ring gear 66a of
the planetary gear mechanism 60a through intermediation of the gear
26. Further, the drive of the stepping motor M12 is transmitted
from the outer gear portion 64a to the outer gear portion 64c of
the ring gear 66c of the planetary gear mechanism 60c. The outer
gear portions 64a and 64c are directly in mesh with each other, and
hence rotation directions of the ring gears 66a and 66c are
opposite to each other.
Thus, when the stepping motor M12 rotates, due to different
rotation directions of the ring gears 66a and 66c, the drive
transmitted to the sun gears 61a and 61c through intermediation of
the inner gear portions 65a and 65c and the planetary gears 62a and
62c acts so as to increase one of the sun gears 61a and 61c in
speed and reduce another of the sun gears 61a and 61c in speed in
accordance with the rotation direction of the stepping motor M12.
Therefore, through transmission of the drive of the stepping motor
M12 in superposition with the drive of the stepping motor M11, the
speed-changing portion 70 is capable of changing the rotation
speeds of the sun gears 61a and 61c. As described above, the sun
gears 61a and 61c are connected to the correction rollers 34a and
34c, respectively. Therefore, through changes in rotation speed of
the sun gears 61a and 61c, a speed difference can be set between
the correction roller 34a and the correction roller 34c.
Specifically, when the stepping motor M12 is stopped, the drive of
the stepping motor M11 causes a rotation speed equal to the
rotation speeds of the carriers 63a and 63c to be output to the sun
gears 61a and 61c. With this action, the correction rollers 34a and
34c rotate at the same speed in the same direction.
When the stepping motor M12 rotates, for example, a rotation speed
which is obtained by adding the rotation speed of the ring gear 66a
to the rotation speed of the carrier 63a is output to the sun gear
61a. Meanwhile, a rotation speed which is obtained by subtracting
the rotation speed of the ring gear 66c from the rotation speed of
the carrier 63c is output to the sun gear 61c. With those actions,
a speed difference is set to the conveyance speeds of the
correction rollers 34a and 34c.
The conveyance speed of the correction roller 34b is set so as to
be equal to the conveyance speeds of the correction rollers 34a and
34c given when the stepping motor M12 is stopped. Further, when the
speed difference is set to the correction rollers 34a and 34c by
rotation of the stepping motor M12, the conveyance speed of the
correction roller 34b is set to a conveyance speed between the
conveyance speed of the correction roller 34a and the conveyance
speed of the correction roller 34c. In particular, in the third
embodiment, the conveyance speed of the correction roller 34b is
set to a median value.
(Skew Feed Correction Control)
FIG. 11 is a block diagram for illustrating a control system for an
original conveying apparatus in the third embodiment. As
illustrated in FIG. 11, the controller 150 controls the stepping
motors M11 and M12 to drive the correction rollers 34a, 34b, and
34c to set the conveyance speed difference between the correction
rollers 34a and 34c. The controller 150 sets the conveyance speed
difference between the correction rollers 34a and 34c based on
detection results of the skew feed detection sensors S1a and S1b.
Other configurations are the same as those in FIG. 6 mentioned
above.
With reference to FIG. 11 and FIG. 12, a description will be
provided of an example of a flow of control in the third
embodiment. When a command to start image reading is given, the CPU
153 engages the feed clutch 59 and, at the same time, operates the
stepping motor M11 (Step S21).
At this time, the pickup roller 31, the conveyance roller 32, and
the retard roller 33 operate, and the correction rollers 34a, 34b,
and 34c rotate at the same speed to wait for the original D. After
elapse of a predetermined time period, when none of the skew feed
detection sensors S1a and S1b detects the leading edge of the
original D (NO in Step S22), the CPU 153 determines that conveyance
abnormality due to jamming of the original D has occurred, stops
the stepping motor M11 (Step S26), and informs a user of the
jamming of the original (sheet) (Step S28).
When at least one of the skew feed detection sensors S1a and S1b
detects the leading edge of the original D before elapse of a
predetermined time period (YES in Step S22), the CPU 153 determines
whether or not there is a time difference between detections by the
skew feed detection sensors S1a and S1b (Step S23). When there is
the time difference (YES in Step S23), the CPU 153 calculates a
skew feed amount of the original D based on the detection results,
and rotates the stepping motor M12 in accordance with the skew feed
amount (Step S27). At this time, the rotation of the stepping motor
M12 is maintained for a time period corresponding to the skew feed
amount (time difference in Step S23). After elapse of this time
period, the rotation of the stepping motor M12 is stopped.
When there is no time difference between the detections by the skew
feed detection sensors S1a and S1b, that is, when the skew feed
detection sensors S1a and S1b detect the leading edge of the
original D at the same time (NO in Step S23), the CPU 153
determines that no skew feed occurs, and continues the rotation of
the stepping motor M11 at the same speed and stops the stepping
motor M12.
When the skew feed detection sensors S1a and S1b are not turned off
after elapse of the predetermined time period (NO in Step S24), the
CPU 153 determines that conveyance abnormality due to jamming of
the original D has occurred, and informs a user of the sheet jam
(Step S28). At this time, the CPU 153 disengages the feed clutch 59
and turns off supply of power to the stepping motor M11 to stop
conveyance of the original D.
When the skew feed detection sensors S1a and S1b are turned off
before elapse of the predetermined time period (YES in Step S24),
the CPU 153 gives the original D to the read rollers 36 and 37.
Then, image reading is performed, and thereafter the original D is
delivered to the original delivery portion 39 by the delivery
roller 38. When there is a next original (YES in Step S25), the CPU
153 continues feeding (Step S21). When there is no next original
(NO in Step S25), the feeding is ended.
In the third embodiment, the speed difference of the conveyance
speeds of the correction rollers 34a and 34c is set through use of
the planetary gear mechanisms 60a and 60c, and hence speed control
of the correction rollers 34a and 34c can be performed through use
of two motors. Further, of the two motors, the stepping motor M11
for driving the correction rollers 34a and 34c can be used also for
driving of the correction roller 34b. Therefore, even with the
configuration in which three conveyance rotary members are
provided, the number of motors being drive sources may be two.
Further, in the third embodiment, while the correction rollers 34a
and 34c are rotated by the stepping motor M11, speed adjustment for
the skew feed correction can be performed with respect to the
correction rollers 34a and 34c through use of the stepping motor
M12. Therefore, as compared to the case of the first embodiment in
which the correction rollers 34a and 34c are rotated by independent
motors, respectively, synchronization of the correction rollers 34a
and 34c in rotation, stoppage, acceleration, and deceleration can
easily be performed, thereby being capable of suppressing variation
in rotation speed of the correction rollers 34a and 34c and in
timing of starting and stopping rotation of correction rollers 34a
and 34c. For example, stoppage and start of the rotation of the
correction rollers 34a and 34c can be performed through stoppage
and activation of one stepping motor M11. Therefore, as compared to
the case of synchronizing stoppage or activation of a plurality of
motors, the operations of the correction rollers 34a and 34c can
easily be synchronized, and conveyance control can be performed
more accurately.
Fourth Embodiment
A fourth embodiment of the present invention will be described with
reference to FIG. 13. In the above-mentioned third embodiment, the
skew feed detection sensors S1a and S1b are arranged upstream of
the correction rollers 34a, 34b, and 34c. In the fourth embodiment,
the skew feed detection sensors S1a and S1b are arranged downstream
of the correction rollers 34a, 34b, and 34c. Other configurations
and actions are the same as those of the above-mentioned third
embodiment. Therefore, redundant illustration and description are
omitted or simplified, and portions different from the third
embodiment will be mainly described.
In the fourth embodiment, the skew feed detection sensors S1a and
S1b are arranged downstream of the correction rollers 34a, 34b, and
34c in the original conveyance direction G. The skew feed detection
sensors S1a and S1b are arranged apart from each other by a
predetermined interval in the width direction H so that respective
detection positions for detecting the leading edge of the original
D are positioned on the same straight line parallel to the width
direction H orthogonal to the original conveyance direction G.
Similarly to the second embodiment, in the fourth embodiment, under
a state in which the original D is nipped by the correction rollers
34a, 34b, and 34c and being conveyed, the skew feed amount of the
original D is detected by the skew feed detection sensors S1a and
S1b. Therefore, the skew feed amount of the original D can be
detected under a state in which the conveyance state is more stable
than that in the third embodiment in which the skew feed amount of
the original D being conveyed by the separation portion E is
detected, thereby being capable of performing more accurate skew
feed correction. Other actions and effects are the same as those of
the second embodiment.
Fifth Embodiment
A fifth embodiment of the present invention will be described with
reference to FIG. 14. In the first to fourth embodiments described
above, a description will be provided of embodiments in which skew
feed correction for an original in an image reading apparatus is
performed. In the fifth embodiment, a description will be provided
of an embodiment for a feeding unit of an electrophotographic image
forming apparatus.
(Image Forming Apparatus)
FIG. 14 is an explanatory view for illustrating a configuration of
a copying machine 200 according to the fifth embodiment of the
present invention. The separation portion E1 and the skew feed
correction portion F2 in the fifth embodiment have the same
configuration as that of the first embodiment. Therefore, in FIG.
14, components which are common to the first embodiment are denoted
by reference symbols which are common to FIG. 6 and FIG. 8, and
redundant description is omitted.
As illustrated in FIG. 14, the copying machine 200 is an
electrophotographic image forming apparatus in which the image
reading unit 110 is arranged in an upper portion of an apparatus
main body 200A. An image forming unit 220 being an example of an
image forming device and a fixing device 230 form an image on a
sheet P having been subjected to skew feed correction by a feeding
unit 210 being an example of a sheet conveying apparatus. The image
forming unit 220 forms a toner image through execution of an
electrophotographic process and transfers the sheet P having been
fed from the feeding unit 210.
The image forming unit 220 includes a charge roller 222, an
exposure device 223, a developing device 224, a transfer roller
225, and a drum cleaning device 226, which are arranged around a
photosensitive drum 211. The charge roller 222 charges a peripheral
surface of the photosensitive drum 221 to a uniform potential. The
exposure device 223 scans and exposes the photosensitive drum 221
with use of a laser beam modulated in accordance with information
of an image to be formed, to thereby form an electrostatic latent
image on the photosensitive drum 221.
The developing device 224 develops an electrostatic latent image on
the photosensitive drum 221 with toner (developer), to thereby form
a toner image on the photosensitive drum 221. The transfer roller
225 receives a transfer voltage applied thereto, and transfers the
toner image on the photosensitive drum 221 to the sheet P having
been fed from the feeding unit 210. The drum cleaning device 226
cleans the photosensitive drum 221 after the transfer of the toner
image onto the sheet P.
The sheet P having the toner image transferred thereto is conveyed
to the fixing device 230 and is heated and pressurized by the
fixing device 230 so that the image is fixed thereon. After that,
the sheet P is delivered to a predetermined delivery tray.
(Feeding Unit)
The feeding unit 210 picks up the sheets P stacked in a cassette
211 one after another and conveys the sheets P to the image forming
unit 220. As described above in relation to the step in which the
sheet P is nipped and conveyed in the image forming unit 220, the
toner image is transferred to the sheet P.
The pickup roller 212 rotates while being held in abutment against
an upper most sheet P stacked in the cassette 211, to thereby feed
the sheet P from the cassette 211 and convey the sheet P to the
separation portion E1.
The separation portion E1 includes a conveyance roller 32A, which
rotates in a sheet conveyance direction, and a retard roller 33A,
which forms a separation nip with the conveyance roller 32A. The
retard roller 33A is driven in a direction of conveying the sheet
in a direction opposite to the sheet conveyance direction of the
conveyance roller 32A, and is capable of being driven by the
conveyance roller 32A. At such separation portion E1, while the
conveyance roller 32A conveys the sheet P on an uppermost surface
to the skew feed correction portion F2 downstream of the separation
portion E1, the retard roller 33A pushes back a multi-fed sheet,
which is fed together with the sheet P, to the cassette 211.
Further, when one sheet is conveyed to the separation portion E1,
the retard roller 33A is driven by the conveyance roller 32A to
rotate, thereby conveying the sheet to the skew feed correction
portion F2.
Similarly to FIG. 5, in the skew feed correction portion F2, the
rollers 34d, 34e, and 34f are held in abutment against the
correction rollers 34a, 34b, and 34c, respectively, to form nips
Na, Nb, and Nc. The skew feed correction portion F2 corrects skew
feed of the sheet P having been given by the separation portion E1
and thereafter conveys the sheet P to a transfer portion at which
the photosensitive drum 221 and the transfer roller 225 are held in
abutment against each other. In the description above, the
configuration described in the first embodiment is applied to the
image forming apparatus according to the fifth embodiment. However,
any one of the second to fourth embodiments may be applied to the
above-mentioned image forming apparatus.
Other Embodiments
The sheet conveying apparatus according to the present invention is
not limited to the specific configurations described in the first
to fourth embodiments. The present invention may be implemented
with other embodiments in which part or all of the configurations
of the first to fourth embodiments are replaced with equivalent
members. The first conveyance rotary member, the second conveyance
rotary member, and the third conveyance rotary member may be
replaced with a conveyance belt stretched around a plurality of
conveyance rollers or support rollers.
In the first to fifth embodiments, the correction roller 34b being
the third conveyance rotary member is arranged downstream of the
separation portion in the sheet conveyance direction. However, the
place of arrangement of the correction roller 34b is not limited to
downstream of the separation portion. For example, the correction
roller 34b may be arranged, for example, at a position far apart to
downstream from the separation portion E, a position downstream of
a source of generation of the conveyance resistance which is
different from the separation portion E, or a position downstream
of the conveyance means different from the separation portion
E.
In the first to fifth embodiments, a description will be provided
of the configuration in which the correction rollers 34a and 34c
are arranged on both sides of the sheet in the width direction
orthogonal to the conveyance direction, respectively, to correct
the skew feed of the sheet. However, the present invention is also
applicable to a configuration in which a plurality of (for example,
two) correction rollers are arranged on each of both sides in the
width direction to correct the skew feed of the sheet. For example,
when two correction rollers are arranged on each of both sides in
the width direction, the two correction rollers on one side in the
width direction may be considered as one first conveyance rotary
member, and the two correction rollers on another side in the width
direction may be considered as one second conveyance rotary member.
Thus, in this case, one or a plurality of correction rollers being
the third conveyance rotary member is arranged between the first
conveyance rotary member and the second conveyance rotary
member.
For example, respective correction rollers arranged upstream of the
first conveyance rotary member and the second conveyance rotary
member in the sheet conveyance direction are assumed to be a pair
of upstream rollers. Similarly, respective correction rollers
arranged downstream in the sheet conveyance direction are assumed
to be a pair of downstream rollers. In this case, one correction
roller being the third conveyance rotary member may be arranged
between the pair of upstream rollers and between the pair of
downstream rollers. Alternatively, one correction roller being the
third conveyance rotary member may be arranged at a center of the
pair of upstream rollers and the pair of downstream rollers in the
sheet conveyance direction and at a center between the first
conveyance rotary member and the second conveyance rotary
member.
In the first to fifth embodiments, a description will be provided
of the configuration in which the correction roller 34b being the
third conveyance rotary member is driven by the motor. However, the
correction roller 34b may be driven to rotate along with conveyance
of the sheet, rather than being driven by the motor. Even with such
configuration, the sheet can be pressed by the correction roller
34b between the correction rollers 34a and 34c. Therefore, as
compared to the case in which the correction roller 34b is not
provided, wrinkles formed in the sheet which are caused by, for
example, the pull-out resistance at the separation portion can be
reduced.
In the third and fourth embodiments, the planetary gear mechanism
is used to change the conveyance speed difference of the correction
rollers 34a and 34c. However, a differential mechanism other than
the planetary gear mechanism may be used. For example, a bevel gear
differential mechanism may be used.
In the third and fourth embodiments, a description will be provided
of the planetary gear which is designed so that the correction
rollers 34a and 34c driven by the stepping motor M11 rotate at the
same rotation speed under a state in which the stepping motor M12
is stopped. However, the planetary gear mechanism may be designed
so that the correction rollers 34a and 34c rotate at the same
rotation speed under a state in which the stepping motor M12
rotates at a predetermined rotation speed V. At this time, the
planetary gear mechanism can be designed so that the conveyance
speed difference is set to the correction roller 34a and 34c by
changing the rotation speed V of the stepping motor M12 to
.+-..DELTA.V. The selection and layout of the drive gear and the
planetary gear in the planetary gear mechanism as well as detailed
structure thereof can be changed or corrected in design in various
manners within the scope of the claims at the time of actual
implementation.
The sheet conveying apparatus according to the embodiments may be
applied to various portions along the conveyance passage of the
sheet in various apparatus other than original conveying apparatus
to be mounted to, for example, a copying machine, a scanner, or a
facsimile machine. As described in the fifth embodiment, the sheet
conveying apparatus may be applied to the feeding unit, which is
mounted to the image forming apparatus and is configured to convey
an unused sheet. The sheet conveying apparatus may be applied to,
for example, a copying machine, a printer, a facsimile, and various
printing machines to feed a sheet having been subjected to the skew
feed correction to the image forming unit. The sheet conveying
apparatus according to the present invention may be applied to a
sheet processing apparatus configured to perform sheet processing
such as aligning and stacking of sheets, book binding, punching,
and stapling to feed a sheet having been subjected to skew feed
correction to a sheet processing unit.
In the sheet conveying apparatus according to the embodiments,
wrinkles are less liable to be formed in the sheet during sheet
conveyance.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
This application claims the benefit of Japanese Patent Application
No. 2017-056177, filed Mar. 22, 2017, and Japanese Patent
Application No. 2018-022280, filed Feb. 9, 2018, which are hereby
incorporated by reference herein in their entirety.
* * * * *